Electronic musical instrument having automatic bass tone selector

ABSTRACT

In an electronic musical instrument comprising an upper keyboard for a melody performance, a lower keyboard for a chord performance and a pedal keyboard for a bass performance there are provided a chord detector for detecting the type of a chord played on the lower keyboard upon depression of the keys thereof; a bass selector responsive to outputs from the chord detector for selectively coupling out from the tone generators bass tone signals corresponding to a note included in the chords played on the lower keyboard; and a gate circuit supplied with the bass tone signals from the bass selector and so designed as to be enabled by operation of one of the keys of the pedal keyboard. The pedal keyboard comprises only one or two keys for controlling one gate circuit supplied with one bass tone signal corresponding to the root note, or two gate circuits supplied respectively with one bass tone signal corresponding to the root note and fifth note included in the chord played on the lower keyboard.

United States Patent m1 ,69 ,6 4 Hiyama [451 Oct. 10, 1972 [54]ELECTRONIC MUSICAL INSTRUMENT OTHER PUBLICATIONS HAVING AUTOMATIC BASSTONE SELECTOR Pages 191-193, from Introduction to Electronic Systems,Circuits, and Devices, D. O. Peder-son, .l. .l.

[72] Inventor: Ryu Hiyama, Hamamatsu, Japan a t"; whinnery McGraw HmBook New or [73] Assignec: Nippon Gakki Seizo Kabushilti Kaisha,Hamamatsu, Japan Primary ExamineF-Lewis H. Myers Assistant ExaminerU.Weldon [22] Flled' March 1971 Attorney-Flynn & Frishauf [2]] Appl. No.:120,651

[57] ABSTRACT 30 Foreign Appucation p -m Data In an electronic musicalinstrument comprising an upper keyboard for a melody performance, alower Dec. 10, 1969 Japan ..44/116848 keyboard for a chord performanceand a pedal DOC. l0, Japan for a bass performance there are provided achord detector for detecting the type of a chord [52] US. Cl ..84/l.l7,84/ L19 played on the lower keyboard upon depression of the [51] lnt.Cl..Gl0h 3/06 keys thereof; a bass selector responsive to outputs [58]Field o f searcli 84/101,133, l. 2 4, l.g6 from the chord detector forselectively coupling out 307/253 from the tone generators bass tonesignals corresponding to a note included in the chords played on the 5References Cited lower keyboard; and a gate circuit supplied with thebass tone signals from the bass selector and so UNITED STATES PATENTSdesigned as to be enabled by operation of one of the I keys of the pedalkeyboard. The pedal keyboard com- 2 11 prises only one or two keys forcontrolling one gate 1 s at a circuit supplied with one bass tone signalcorrespond- TCTIIICS X to the too note, or two g circuits pp 3476864Munch l al "84,124 x respectively with one bass tone signalcorresponding 3,535,972 [0/1970 Teramshi ..84/l.26 X to the root noteand fif note included in the chord played on the lower keyboard.

1i l2 Figures ,5 T UPPER ONE KEYBOA CQLORING RD FIgTER 3 ,7 1 5 16 TONES LOWER TONE GENERATORS KEYBOARD COLOR'NG I FILTER 9 CHORD DETECTOR l 1011 I TONE BASS GATE 1 s COLORING ELECTOR FILTER PEDAL KEY PATENIEBlJcI10 m2 SHEET 1 OF 5 F I G. l /5 TONE {6 UPPER COLORING KEYBOARD FILTER j5 6 1 7 1 1 3 z 2 TONE S LOWER TONE GENERATORS KEYBOARD ga -g2 AMP.

i CHORD d DETECTOR 12 4 1 10 TONE J BASS I -cO| OR|Ns SELECTOR 4 FILTER4 I F G 2 PEDAL KEY -L i D1 R o r r 2 (c1 \P -P1 W1 k 5:22

0 [671 K x a P 3 m] A m] x 5X. E [D7] x A [a A I i 82 $8 \59 510 11 $12\PAIENTEMBI 10ml 3.697664 SHEEI 2 BF 5 PATENTED B 10 I972 3.697.664

LOWER PEDAL [c] [F] [e71 c1 FIG.5C

BASS

PATENTED 3.697.664

SHEET l [1F 5 UPPER q TONE 55 KEYBOARD gf l-gg 3 8 TONE LOWER z r Rl NGA M p i N CHORD DETECTOR {10A 11 A BASS .GATE

QHFCTORI i TONE Q 13A COLORING- BASS GATE 7 FILTER SELECTOR n h @11814B-U U-14A F I G 6 PEDAL KEYS T0 TONE COLORING FILTER FIG.7

PATENTEMBI 10 1972 3697.664

SHEETSUFS FIG.8A

[c] [F] [6 1 [g1 LOWER PEDAL FIG.8B

[c1 [F1 [6 1 [c LOWER j PEDAL L FIG.8C

[C] [F] [67] [C] ELECTRONIC MUSICAL INSTRUMENT HAVING AUTOMATIC BASSTONE SELECTOR The present invention relates to an electronic musicalinstrument and more particularly to improvements to facilitate a bassperformance on the pedal keyboard.

With a conventional electronic organ having upper, lower and pedalkeyboards, a melody performance is generally played by operation of theupper keyboard with the right hand, a chord performance by operation ofthe lower keyboard with the left hand, and a bass performance byoperation of the pedal keyboard with the left foot. In this case, theleft hand chord performance and the left foot bass performance arecommonly conducted with a certain rhythmic pattern, like that of a marchor waltz. However, the cord and bass performances with the left hand andleft foot require considerable skill, because they have to be played inconjunction with the melody performance with the right hand.Particularly, a beginner finds it extremely difficult to carry out arhythmic accompaniment of chord and bass exactly conforming with amelody performance. The chord performance is effected by depressing someof the keys of the lower keyboard at the same time as well asrhythmically, and the bass performance is carried out by selectivelydepressing one after another those of the thirteen pedal keysconstituting a full octave which conform with the chord performance.Accordingly, the bass performance presents greater difficulties to thebeginner than the chord performance.

It is, accordingly, the object of the present invention to provide anelectronic musical instrument facilitating a bass performance.

The object of the present invention is attained in that there areprovided a chord detector for detecting the type of chord played on thelower keyboard upon depression of the keys thereof; at least one bassselector for selectively coupling out from the tone generators bass tonesignals corresponding to a note included in the chord in response tooutput signal from the chord detector; and at least one bass gatecircuit for receiving the bass tone signal from the bass selector, thegate circuit being conducted (i.e., enabled) upon depression of one ofthe the keys of the pedal keyboard. In accordance with the presentinvention it is only required that the pedal keyboard be provided withone or two keys.

The present invention can be more fully understood from the followingdetailed description when taken in conjunction with the appendeddrawings, in which:

FIG. I is a block diagram of an electronic musical instrument accordingto an embodiment of the present invention;

FIG. 2 is a circuit diagram of a chord detector shown in FIG. I;

FIG. 3 represents a bass selector circuit and gate circuit shown in FIG.I;

FIG. 4 illustrates a bass selector circuit and gate circuit according toanother embodiment of the invention;

FIG. 5A, 5B and 5C show musical notations useful in explaining theoperation of the electronic musical instrument of FIG. I;

FIG. 6 is a block diagram of an electronic musical instrument accordingto another embodiment of the invention;

FIG. 7 is a circuit diagram of the bass selectors of FIG. 6; and

FIG. 8 indicates musical notations useful in explaining the operation ofthe electronic musical instrument of FIG. 6.

Referring to FIG. 1, tone signals from tone generators I are distributedto the upper, lower and pedal keyboard channels 2, 3 and 4. As is wellknown, the upper keyboard channel 2 includes an upper keyboard 5 havingkey switch circuits for selectively keying tone signals from the tonegenerators I upon depression of the keys and tone coloring filters 6 forconverting the selected tone signals to musical tone signals. Similarly,the lower keyboard channel 3 includes a lower keyboard 7 having keyswitch circuits for selectively keying tone signals from the tonegenerators I upon depression of the keys and tone coloring filters 8 forconverting the selected tone signals to musical tone signals.

According to the present invention, there is provided a chord detector 9for detecting the type of chord played by operation of the lowerkeyboard 7. Further, the pedal keyboard channel 4 of the electronicmusical instrument of the invention includes a bass selector 10 forselectively coupling out from the tone generators 1 bass tone signalscorresponding to a note, preferably the root note included in thechords, in response to output signals from the chord detector 9; a bassgate cir' cuit II supplied with bass tone signals from the bass selectorl0; and tone coloring filters l2 supplied with the bass tone signal uponconduction of the bass gate circuit 11. As illustrated in FIG. I, thebass gate circuit II is provided with a key switch I3 and is conducted(i.e., enabled) by a single key I4 constituting the pedal keyboard.Depression of the pedal key 14 actuates the key switch I3 to conduct thegate circuit 11, causing a bass tone signal to be supplied from the bassselector I0 to the tone coloring filters I2.

Musical tone signals from the respective channels 2, 3 and 4 areamplified by an amplifier I5 and converted to audible sounds by a loudspeaker 16.

With an electronic organ of FIG. 1, a melody perfonnance is conducted asusual by operation of the upper keyboard 5 with the right hand, and achord performance by operation of the lower keyboard 7 with the lefthand. While the chord performance is being played on the lower keyboard,the type of chord played is distinguished by the chord detector 9, and abass tone signal corresponding to one of the notes included in the chordis selected by the bass selector [0 responsive to the output of thechord detector 9 and then supplied from the tone generators I to thegate circuit II. The rhythmic operation of the pedal key 14 causes basstone signals to be supplied to the tone coloring filters 12 in a rhythmpattern corresponding to the operation of the pedal key 14. Namely, thepresent invention enables a bass performance to be carried out simply byoperation of a single pedal key without the necessity of selecting oneof a plurality of (thirteen) pedal keys as is the case with the priorart electronic organ.

There will now be described by reference to FIG. 2 the chord detector 9of FIG. I. The chord detector 9 comprises a matrix circuit having aplurality of column lines, row lines and diodes positioned at theprescribed intersections of both lines. The matrix circuit has twelvecolumn lines L, to L,, corresponding to the notes of one octave, theends on one side of the column lines being grounded by normally open keyswitches S, to 8,, operated by the respective keys of the lower keyboard7. The switches actuated by the keys corresponding to the same notes inthe different octaves are respectively connected to the same commoncolumn lines included in the matrix circuit. The ends on the other sideof the column lines are connected through a resistor R, to one end of acommon power source 20, the other end of which is grounded. The matrixhas the same number of row lines or output lines 0,, 0,, 0,, as thekinds of chords to be played on the lower keyboard. FIG. 2 indicatesseven row lines representing Chords L 11], I]. r-l. 1] and [8]. The endson one side of the row lines are grounded through resistors R, and R, Atthe prescribed intersections between the row lines denoting these chordsand column lines are connected diodes in the forward direction withrespect to the polarity of the power source 20 to which the column linesare connected to detect. For example, for chord [C], there are connecteddiodes D of the indicated polarity to three intersections defined by rowline 0, with column line L,, connected to switch S, operated by the keyof the lower keyboard corresponding to note C included in chord [C],column line L, connected to switch 8,, corresponding to note E andcolumn line L, connected to switch S, corresponding to note G.

Referring to the operation of the aforesaid chord detector, the diodesare connected to the intersections of the row lines and column lines inthe forward direction with respect to the positive source voltage, sothat the potential of the detection terminal of the row line, or thejuncture between resistors R, and R, is normally kept positive.Depression of the keys of the lower keyboard corresponding to, forexample, notes C, E and causes switches S,, S, and S, to be closed andin consequence column lines L,, L, and L, to be grounded. Accordingly,the power source 20 is shortcircuited with column lines L,, L, and L, bythe resistor R,, preventing row line 0, connected to column lines L,, L,and L, by the diodes from being impressed with voltage, so that thepotential of the detection terminal P, of row line 0,, that is, thevoltage across the resistor R, is reduced to zero. At this time, thepotentials ot'the detection terminals P,, P .of the other row lines arestill kept positive. From the fact that the potential of the detectionterminal of row line 0, associated with the chord [C] was changed frompositive to zero, the chord performed by operation of the lower keyboardis distinguished as [C] The detected output controls the bass selector10. This selector may be constructed as illustrated in FIG. 3.

FIG. 3 illustrates one of the selector circuits included in the bassselector l0 and a common bass gate circuit II, the selector circuitbeing associated with the chord [C ]v The selector circuit includes, forexample, an NPN type transistor T, the collector of which is connectedto a positive power source through a resistor 2!, the emitter of whichis grounded through a capacitor 22 and the base of which is connected tothe juncture between resistors 23 and 24 which are disposed between thepower source and earth. The base of the transistor T, lS normallysupplied by the tone generators l with a bass tone signal C,corresponding to the root note C of the chord [C]. The emitter oftransistor T, is connected to the output terminal P, included on thechord detector 9 for detection of the chord [C] shown in FIG. 2 througha diode 25 disposed in the same direction as the base-emitter diode oftransistor T,. A bass tone signal from the selector circuit is drawn outfrom the collector of transistor T, through a coupling capacitor 26 andsupplied to the bass gate circuit ll. Bass tone signals from the otherselector circuits included in the bass selector 10 are also impressed onthe same gate circuit ll through respective coupling EPEFlBP',

The bass gate circuit ll includes, for example, an NPN type transistorT,, the collector of which is connected to a power source (+V,) througha resistor 27, the base of which is connected to the juncture betweenresistors 28 and 29arranged in series between the power source andground, and also to the capacitor 26 of the selector circuit, and theemitter of which is grounded through resistors 30 and 3! and the keyswitch 13 of FIG. 1 in this order. The juncture between the resistors 30and 3| is connected to a control voltage source V, through a resistor32, and a circuit including the resistor 3| and key switch l3 connectedin series is shunted by a capacitor 33. The output from the gate circuit11 is drawn out from the collector of the ansistor [:L'HQEEE a 2 294There will now be described the operation of the circuit of FIG. 3. Whenthe output terminal P, of an out put line 0, for detection of the chord[C] of FIG. 2 is supplied with positive voltage by the power source 20,the transistor T, is rendered inoperative to cease the supply of thebass tone signal C, to the bass gate circuit ll. When the chord [C] isplayed on the lower keyboard, namely when there are depressed the keyscorresponding to the notes C, E and G, then the potential of the outputterminal P, is reduced to zero as shown in FIG. 3 to cause thetransistor T, to be rendered operative and the bass tone signal C, to beipt ooresm The capacitor 33 connected to the emitter of transistor T, ofthe bass gate circuit It is charged by the voltage source (+V,, whosevoltage is high enough to render the transistor T, normallynonconductive. When the key switch 13 is closed by operation of thepedal key 14, the charged voltage is dissipated through the resistor 31and key switch 13 to decrease the emitter potential and in consequencerender the transistor T, operative. Namely, when the key switch I3 isclosed, a bass tone signal from the bass selector circuit T, which hasalready been energized is drawn out from the collector of transistor T,of the bass gate circuit II. The capacitor 22 connected to the emitteroftransistors T, of the selector circuit I0 is intended to allow thetransistors T, to remain conductive for a predetermined length of time(preferably about 0.5 second), though, after the lower keyboard ceasesto be operated, the voltage impressed on the output terminal P, of thechord detector 9 rises from zero to the same level as the sourcevoltage.

The selector circuit including the transistor T, shown in FIG. 3 may beallowed to concurrently act as the gate circuit including the transistorT,. FIG. 4 illustrates such case. The same parts of FIG 4 as those ofFIG. 3 and denoted by the same numerals. The juncture between the diode25 connected to the emitter of transistors T, included in the bassselector circuit and the output tenninal P, of the chord detector 9 isconnected to the control voltage source (+V,) through a circuitincluding a diode 3S and the normally closed key switch 13 connected inseries. The diodes 35 is disposed in the forward direction with respectto the voltage source (+V,). The transistors T, of the other selectorcircuits are supplied with the control voltage through respective diodes35, and common key switch 13.

In the circuit of FIG. 4, while the key switch 13 is closed, thetransistor T, is rendered inoperative due to the control voltage V,though the potential of the output terminal P, of the chord detector 9is made to otherwise become zero. Opening of the key switch 13 bydepression of the pedal key 14 separates the emitter circuit oftransistor T, from the control source and thus a bass tone signal can bederived from the collector of transistor T, as long as the potential ofthe output terminal P, of the chord detector 9 is zero.

There will now be described by reference to FIGS. 5A, 5B and 5C theoperation of the electronic musical instrument of FIG. 1. FIG. 5Aillustrates musical notations for the chord and bass performances whichit is desired to play on the lower and pedal keyboards. It will beapparent from the illustration that the chords [C], [F], [6-,] and [C]are played in turn at the respective measures and that the bassperformance is conducted by the root notes of the chords defined by themeasures and that the bass performance is conducted by the root notes ofthe chords defined by the measures.

FIG. 58 indicates the manner of operation of the lower and pedalkeyboards when the notations of FIG. 5A are to be played. As seen fromthe illustration, the lower keyboard should be rhythmically operatedfour times for each measure, whereas a single key constituting the pedalkeyboard has only to be operated twice for each measure.

FIG. SC shows musical tones produced by the keyboard operation indicatedin FIG. 58. It is seen that bass tones last longer than chord tones.This is due to the action of the capacitor 22 connected to the emitterof transistors T, included in the bass selector circuit as shown inFIGS. 3 and 4.

The foregoing embodiment relates to the case where the bass performancewas carried out according to the root note on the chord alone, that is,only by operation of a single pedal key. However, the bass performancemay also be conducted according to both the root and fifth notes of thechord and by operation of two pedal keys to provide a better musicaleffect. This embodiment is presented in FIG. 6.

According to the embodiment of FIG. 6, the pedal keyboard channel 4includes a first bass selector 10A for selectively drawing out a basstone signal corresponding to the root note of the chord; a second bassselector 103 for drawing out a bass tone signal corresponding to thefifth note of the chord; a first bass gate circuit IIA supplied with thebass tone signal by the first bass selector 10A; and a second bass gatecircuit supplied with the bass tone signal from the second bass selector10B. Output signals from the first and second bass gate circuits A and11B are conducted to the common tone coloring filters 12. The pedalkeyboard is comprised of two keys 14A and 148. The key switches 13A and13B actuated by the keys NA and 148 respectively are disposed in thefirst and second bass gate circuits 11A and 118. FIG. 7 shows thecircuits of the bass electors 10A and 10B of FIG. 6. These gate circuits10A and 10B are of the same arrangement as that of FIG. 3 and the sameparts of FIG. 7 as those of FIG. 3 are denoted by the same numerals.Elements included in the selector circuit of the root note are indicatedby reference notations suffixed with the letter A and elements includedin the selector circuit of the fifth note bear reference notationssuffixed with the letter B.

In this case, the base of transistor T of the selector circuit 10A forthe root note is supplied with a bass tone signal C, corresponding tothe root note C of the chord [C]. And the the base of transistor T, ofthe selector circuit 103 for the fifth note is supplied with a bass tonesignal G, corresponding to the fifth note G of the chord [C]. Theemitters of transistors T,,, and T, are jointly connected to the outputterminal P, of the chord detector 9 through diodes 25A and 25Brespectively.

Outputs from the selector circuits of the root notes of the other chordsare coupled to the gate circuit A. Similarly, outputs from the selectorcircuits of the fifth notes of the other chords are coupled to the gatecircuit 1 1B. The circuit of FIG. 7 arranged as described above isoperated in the same manner as that of FIG. 3. When the potential of theoutput terminal P, of the chord detector 9 decreases as shown in FIG. 7,the selector circuits T and T,,, are jointly rendered operative to causehas tone signals C, and G, to be drawn out therefrom and supplied to thegate circuits 11A and 118. These circuits A and 11B are alternatelyconducted by either of the two pedal keys 14A and 148.

FIG. 8A illustrates the musical notations of the chord and bassperformances which it is desired to play by the electronic musicalinstrument of FIG. 6. It will be apparent from the illustration that thebass performance is carried out alternately according to either of theroot and fifth notes of the chord. To this end, the two pedal keys haveonly to be operated alternately as shown in FIG. 88. Consequently,desired musical tones can be produced as shown in FIG. 8C.

The foregoing embodiments of FIGS. 3 and 7 relate to the cases where wasconducted a bass performance according to the root note of one chord andthe root and fifth notes thereof respectively. Where it is desired tocarry out a bass performance by three or more bass tone signals withrespect to one chord, namely, where, in case of, for example, the chord[C], it is desired to produce three bass tones corresponding to the rootnote C, fifth note G and other note E of the chord, it is only requiredto use one more bass selector circuit and one more gate circuit, and onemore pedal key for control of the additional gate circuit.

What I claim is:

I. An electronic musical instrument comprising:

a plurality of tone generators;

an upper keyboard for melody performance having key switch circuits forselecting tone signals from said tone generators",

a lower keyboard for chord performance having key switch circuits forselecting tone signals from said tone generators;

a matrix-connected chord detector coupled to said lower keyboard fordetecting and identifying the type of chords played on said lowerkeyboard by detecting which keys of said lower keyboard are actuated,said chord detector comprising:

a plurality of column lines, one end of each of which is groundedthrough a detector switch actuated through operation of said lowerkeyboard and the other end ofeach of which is connected to a DC. sourcethrough a resistor;

a plurality of row lines provided for each different chord andintersecting said plurality of column lines, said row lines beinggrounded at one end through a resistor; and

at least two diodes connected in the forward direction with respect tosaid D.C. source polarity between each row line and at least two of saidplurality of column lines connected to said de tector switches operatedby the keys of said lower keyboard actuated according to the chord,whereby upon operation of the keys of said keyboard to play a chord,those of said plurality of column lines which are connected to saiddetector switches actuated by the keys are grounded and said powersource is also grounded through resistors connected to the column lines,causing said row line to be disconnected from said DC. power source andin consequence the voltage across said resistor connected to said rowline to be varied, thus providing detection of the type of chord played;

at least one bass selector coupled to said chord detector and to saidtone generators and responsive to the output of said chord detector forcoupling out from said tone generators selected bass tone signalscorresponding to one predetermined note included in said detector chordsbeing played;

at least one gate circuit coupled to said bass selector for receivingsaid selected bass tone signals from said bass selector;

said has selector and gate circuit including:

a common transistor having an emitter, base and collector;

a first diode disposed in the forward direction with respect to thebase-emitter diode junction of said common transistor and coupling saidate cir uit to c u le e selected bass tone s| nal feceived by sa|d gatelrcuit to an output terr inal to cause bass performance.

2. The electronic musical instrument according to claim 1 wherein saidbass selector includes a plurality of selector circuits, each selectorcircuit being connected to receive a bass tone signal corresponding tothe respective root notes of the chords played on said lower keyboard,said gate circuit being connected to said each selector circuit and saidpedal keyboard is provided with a signal key and including means forselectively operating said gate circuit by its operation. single 3. Theelectronic musical instrument claim I wherein:

said bass selector comprises first and second selectors coupled to saidtone generators, each selector including a plurality of selectorcircuits and each selector circuit of said first bass selector beingresponsive to said chord detector to couple out from said tonegenerators a bass tone signal corresponding to the respective rootnotes, and each selector circuit of said has selector being responsiveto said chord detector to couple out from said tone generators a basstone signal corresponding to the respective fifth notes of the chordsplayed on said lower keyboard;

said gate circuit comprises first and second gate circuits, said firstgate circuit being connected to said first bass selector and said secondgate circuit being connected to said second bass selector; and saidpedal keyboard is provided with at least two keys which include meansfor selectively operating said first and second gate circuitsrespectively. 0 t

according to

1. An electronic musical instrument comprising: a plurality of tonegenerators; an upper keyboard for melody performance having key switchcircuits for selecting tone signals from said tone generators; a lowerkeyboard for chord performance having key switch circuits for selectingtone signals from said tone generators; a matrix-connected chorddetector coupled to said lower keyboard for detecting and identifyingthe type of chords played on said lower keyboard by detecting which keysof said lower keyboard are actuated, said chord detector comprising: aplurality of column lines, one end of each of which is grounded througha detector switch actuated through operation of said lower keyboard andthe other end of each of which is connected to a D.C. source through aresistor; a plurality of row lines provided for each different chord andintersecting said plurality of column lines, said row lines beinggrounded at one end through a resistor; and at least two diodesconnected in the forward direction with respect to said D.C. sourcepolarity between each row line and at least two of said plurality ofcolumn lines connected to said detector switches operated by the keys ofsaid lower keyboard actuated according to the chord, whereby uponoperation of the keys of said keyboard to play a chord, those of saidplurality of column lines which are connected to said detector switchesactuated by the keys are grounded and said power source is also groundedthrough resistors connected to the column lines, causing said row lineto be disconnected from said D.C. power source and in consequence thevoltage across said resistor connected to said row line to be varied,thus providing detection of the type of chord played; at least one bassselector coupled to said chord detector and to said tone generators andresponsive to the output of said chord detector for coupling out fromsaid tone generators selected bass tone signals corresponding to onepredetermined note included in said detector chords being played; atleast one gate circuit coupled to said bass selector for receiving saidselected bass tone signals from said bass selector; said bass selectorand gate circuit including: a common transistor having an emitter, baseand collector; a first diode disposed in the forward direction withrespect to the base-emitter diode junction of said common transistor andcoupling said emitter to said chord detector; a capacitor coupling saidemitter to ground; means coupling the juncture between said first diodeand said chord detector to a control power source, said coupling meansincluding a normally closed pedal switch opened by one pedal key and asecond diode disposed in the forward direction with respect to saidcontrol power source; said base being connected to the corresponding oneof said tone generators; and a coupling capacitor connected to saidcollector; and a pedal keyboard for bass performance provided with atleast one key for selectively operating said gate circuit to couple theselected bass tone signals received by said gate circuit to an outputterminal to cause bass performance.
 2. The electronic musical instrumentaccording to claim 1 wherein said bass selector includes a plurality ofselector circuits, each selector circuit being connected to receive abass tone signal corresponding to the respective root notes of thechords played on said lower keyboard, said gate circuit being connectedto said each selector circuit and said pedal keyboard is provided with asignal key and including means for selectively operating said gatecircuit by its operation. single
 3. The electronic musical instrumentaccording to claim 1 wherein: said bass selector comprises first andsecond selectors coupled to said tone generators, each selectorincluding a plurality of selector circuits and each selector circuit ofsaid first bass selector being responsive to said chord detector tocouple out from said tone generators a bass tone signal corresponding tothe respective root notes, and each selector circuit of said bassselector being responsive to said chord detector to couple out from saidtone generators a bass tone signal corresponding to the respective fifthnotes of the chords played on said lower keyboard; said gate circuitcomprises first and second gate circuits, said first gate circuit beingconnected to said first bass selector and said second gate circuit beingconnected to said second bass selector; and said pedal keyboard isprovided with at least two keys which include means for selectivelyoperating said first and second gate circuits respectively.